Investigating ring polymer dynamics dwells on the basic understanding of polymer motions in melts. Since chain ends determine to a large extend the properties of dense polymer systems, the study of polymer rings allows fundamental assumptions of polymer physics to be tested. Rings cannot display contour length fluctuations and even more it is expected that the tube concept is not applicable at all. Instead a lattice animal like conformation may describe the topological interactions in large ring melts. We present neutron scattering data on the structure and dynamics of melts from polyehtylenoxide rings with molecular weights up to ten times the entanglement mass of the linear counterpart.1) The data reveal a very compact conformation displaying a structure approaching a mass fractal as hypothesized by recent simulation work. The dynamics is characterized by a fast Rouse relaxation of sub units (loops) and the slower dynamics displaying a lattice animal like loop displacement. The loop size is an intrinsic property of the ring architecture and is independent of molecular weight. This experimental observation of the space time evolution of segmental motion in ring polymers illustrates the dynamic consequences of their topology that is unique among all polymeric systems of any other known architecture. We will also address first results on the dynamics of rings in blends with linear polymers. 1)Physical Review Letters 131, 168302 (2014)

Molecular scale dynamics of ring polymers: a neutron spin echo study

249th National Meeting (2015)

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